Naturopathic Foundation's blogs are written by naturopathic doctors that work at Naturopathic Foundation's Health Clinic in Markham, Ontario. The blogs provide detailed information on how to prevent and treat disease.

Tuesday, October 30, 2012

How Much Vitamin D is Safe?

By Dr. Iva Lloyd, ND

There has been a lot in the media over the last couple of years encouraging people to take high doses of vitamin D. The potential benefits of supplementation include:

fewer falls and fractures

increased bone density

prevention of influenza virus

prevention or reduction in asthma attacks

increased insulin sensitivity

decreased blood pressure

and the prevention of some cancers and autoimmune disease

Not that long ago the recommended dosage for vitamin D supplementation was 400 iu / day. Currently it is not unusual for individuals to be dosing at 10 to 20 times that amount. Lately it has been questioned whether or not the benefits of vitamin supplementation are still achieved at high dosages. The concerns include:

Serum 25 hydroxyvitamin D (the standard blood test for vitamin D status) may not be a reliable indicator as it's half-life is 3 weeks. Also, 25 hydroxyvitamin D is only one of more than 50 vitamin D metabolites in blood and it is questionable as to the validity of using it as the primary indicator.

The safety and efficacy of vitamin D supplementation cannot be inferred from data regarding the safety and efficacy of sunlight exposure. Many of the promoted benefits of vitamin D supplementation are actually from studies looking at sunlight exposure itself.

There are some conditions, such as celiac disease, Crohn's, multiple sclerosis and some cancers where dosing high with vitamin D may be advantageous. The new research indicates that 800 to 1200 IUs / day is generally effective for most people. Ideally, the best way to ensure adequate vitamin D status is to enjoy 5-15 minutes of sunlight exposure 2 to 3 times a week between 10 a.m. and 3 p.m.

If you have any questions about the optimal amount of vitamin D supplementation for yourself, talk to your naturopathic doctor.